An experiment was conducted to estimate the effect of smoking on the blood pressure of a group of 39 cigarette smokers. the difference for each participant was obtained by taking the difference in the blood pressure readings at the beginning of the experiment and again five years later. the sample mean increase, measured in millimetres of mercury, was
x = 9.9.
the sample standard deviation was
s = 5.1.
estimate the mean increase in blood pressure that one would expect for cigarette smokers over the time span indicated by the experiment.
find the 95% margin of error. (round your answer to two decimal places.)
describe the population associated with the mean that you have estimated.
the population is made up of the differences in blood pressure for all smokers and smokers over 40.the population is made up of the differences in blood pressure for all smokers under 40 and smokers over 40. the population is made up of the differences in blood pressure for all smokers and nonsmokers. the population is made up of the differences in blood pressure for all smokers between the beginning of the experiment and five years later. the population is made up of the differences in blood pressure for all smokers and nonsmokers between the beginning of the experiment and five years later.
3.–/7 pointsmendstatc4 9.e.064.
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acid rain, caused by the reaction of certain air pollutants with rainwater, is a growing problem in the united states. pure rain falling through clean air registers a ph value of 5.7 (ph is a measure of acidity: 0 is acid; 14 is alkaline). a sample of n = 50rainfalls produced ph readings with x = 3.3 and s = 0.5. do the data provide sufficient evidence to indicate that the mean ph for rainfalls is more acidic (ha: μ < 5.7 ph) than pure rainwater? test using α = 0.05. note that this inference is appropriate only for the area in which the rainwater specimens were collected.
state the null and alternative hypotheses.
h0: μ = 5.7 versus ha: μ < 5.7h0: μ = 5.7 versus ha: μ > 5.7 h0: μ ≠ 5.7 versus ha: μ < 5.7h0: μ < 5.7 versus ha: μ = 5.7h0: μ > 5.7 versus ha: μ < 5.7
find the test statistic and rejection region. (round your answers to two decimal places. if the test is one-tailed, enter none for the unused region.)
test statistic z = rejection region z > z <
state your conclusion.
h0 is rejected. there is insufficient evidence to indicate that the average ph for rainfalls is more acidic than pure rainwater. h0 is rejected. there is sufficient evidence to indicate that the average ph for rainfalls is more acidic than pure rainwater. h0 is not rejected. there is insufficient evidence to indicate that the average ph for rainfalls is more acidic than pure rainwater. h0 is not rejected. there is sufficient evidence to indicate that the average ph for rainfalls is more acidic than pure rainwater.